use thiserror::Error;
use git2::{ErrorClass, ErrorCode};

/// Detailed git error with actionable hint
#[derive(Debug)]
pub struct GitDetailedError {
    pub code: ErrorCode,
    pub class: ErrorClass,
    pub message: String,
    pub hint: String,
}

impl std::fmt::Display for GitDetailedError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.message)
    }
}

#[derive(Error, Debug)]
pub enum EmpveError {
    #[error("Config error: {0}")]
    Config(String),

    #[error("Git error: {0}")]
    Git(#[from] git2::Error),

    #[error("IO error: {0}")]
    Io(#[from] std::io::Error),

    #[error("TOML parse error: {0}")]
    TomlParse(#[from] toml::de::Error),

    #[error("TOML serialize error: {0}")]
    TomlSerialize(#[from] toml::ser::Error),

    #[error("Repository not found: {0}")]
    RepoNotFound(String),

    #[error("Repository already exists: {0}")]
    RepoExists(String),

    #[error("Script not found: {0}")]
    ScriptNotFound(String),

    #[error("Invalid repository identifier: {0}")]
    InvalidRepo(String),
}

impl EmpveError {
    /// Get a user-friendly hint for resolving this error
    pub fn hint(&self) -> Option<String> {
        match self {
            EmpveError::Git(e) => Some(git_error_hint(e)),
            EmpveError::RepoNotFound(_) => Some("Check the repository name and try again. Use 'empeve browse' to see available scripts.".to_string()),
            EmpveError::RepoExists(_) => Some("Use 'empeve remove' first if you want to replace it.".to_string()),
            EmpveError::ScriptNotFound(_) => Some("Check script name or run 'empeve status' to see available scripts.".to_string()),
            EmpveError::InvalidRepo(_) => Some("Use format 'user/repo' for GitHub or a full git URL.".to_string()),
            _ => None,
        }
    }
}

/// Generate a user-friendly hint from a git2 error
pub fn git_error_hint(error: &git2::Error) -> String {
    match (error.code(), error.class()) {
        (ErrorCode::NotFound, ErrorClass::Reference) => {
            "The specified branch or ref was not found. Check if it exists on the remote.".to_string()
        }
        (ErrorCode::NotFound, ErrorClass::Repository) => {
            "Repository not found. Verify the URL is correct and you have access.".to_string()
        }
        (ErrorCode::Auth, _) => {
            "Authentication failed. The repository may be private or credentials are invalid.".to_string()
        }
        (ErrorCode::Certificate, _) | (_, ErrorClass::Ssl) => {
            "SSL/TLS certificate error. Check your system certificates or network.".to_string()
        }
        (ErrorCode::Locked, _) => {
            "Repository is locked. Another process may be using it. Try again later.".to_string()
        }
        (ErrorCode::Exists, _) => {
            "The destination already exists. Use --force to overwrite.".to_string()
        }
        (ErrorCode::BareRepo, _) => {
            "Cannot perform this operation on a bare repository.".to_string()
        }
        (ErrorCode::UnbornBranch, _) => {
            "The repository has no commits yet.".to_string()
        }
        (ErrorCode::Uncommitted, _) => {
            "There are uncommitted changes. Commit or stash them first.".to_string()
        }
        (_, ErrorClass::Net) | (ErrorCode::GenericError, ErrorClass::Os) => {
            "Network error. Check your internet connection.".to_string()
        }
        (_, ErrorClass::Checkout) => {
            "Checkout failed. There may be conflicting local changes.".to_string()
        }
        (_, ErrorClass::FetchHead) => {
            "Failed to update FETCH_HEAD. Try running 'empeve clean' and reinstalling.".to_string()
        }
        _ => {
            format!("Git operation failed ({:?}/{:?})", error.class(), error.code())
        }
    }
}

pub type Result<T> = std::result::Result<T, EmpveError>;